The semantic jāmiʿ interacts with grammatical form. Two nominal clauses, two verbal clauses, or verbal clauses with matching temporal orientation usually permit a more direct comparison. A shift of tense can instead create a new rhetorical dimension.
Example 1: “Zayd reads and ʿAmr writes” compares concurrent habits.
Example 2: “Zayd came and ʿAmr left” reports past events.
Example 3: “Zayd arrived and ʿAmr will write” changes the time reference; its coordination requires a contextual reason.
These are rhetorical considerations, not unconditional rules of grammatical impossibility. A deliberate tense shift may itself be the intended effect.